Relapse in acute lymphoblastic leukemia as a function of white blood cell and absolute neutrophil counts during...

Several reports document an inverse correlation between bioavailability of maintenance chemotherapeutic agents and the likelihood of relapse in childhood. White blood cell counts (WBC) and absolute neutrophil counts (ANC) are easily ascertainable parameters which might be expected to reflect plasma levels of chemotherapy. To determine whether WBC and ANC predict outcome of children with acute lymphoblastic leukemia (ALL), we did a multivariate analysis of means of these values during maintenance therapy in patients with ALL treated on a single protocol. Of the 52 patients, 15 (29%) relapsed. For those still disease-free, minimum time of follow-up is 7-8/12 years. During the first year of maintenance therapy, mean WBC (x 10(3)/mm3) in the relapsed and nonrelapsed groups were 4.5 +/- 0.9 and 3.9 +/- 0.7, respectively (p = 0.03); mean ANC (x 10(3)/mm3) were 3.0 +/- 0.9 and 2.5 +/- 0.6 (p = 0.05). However, the range of values was large with considerable overlap between the two groups. There was no obvious difference in distribution of values when confounding prognostic features were adjusted for in the analysis. No significant differences were seen between WBC or ANC during the second year of therapy. Larger numbers of patients will be needed to ascertain whether specific guidelines for dosage modifications can be made on the basis of serial WBC. Future pharmacokinetic studies should look at possible correlations with mean WBC and ANC.